The present invention relates to an apparatus for wetting fibrous material, in particular wood, woodchips and waste paper.
Woodchips with a size of about 4 cm×2 cm×1 cm are decomposed into their fiber constituents by refiner grinding. This gives rise to the TMP fibrous substance required for papermaking (TMP=thermomechanical pulp). The higher the moisture content of the woodchips is, the more elastic, the softer and the more pliable is the composite fibrous structure within the woodchips and the individual fibers contained in the woodchip. Since, with an increasing length of the fibers, their strength increases, and such fibers are suitable for making high-grade papers, the aim is for the fibers to have as high moisture and elasticity as possible during the refiner grinding.
EP 1 051 551 discloses a method for wetting fibrous material composed of waste paper having a multilayer coating, such as, for example, beverage pasteboard. In beverage pasteboard, as it is known, both sides of the paper are coated with plastic and/or aluminum.
An apparatus and a method for the recovery of cellulose fibers from waste paper are known from U.S. Pat. No. 5,496,439. Here, the waste paper surrounded by a liquid is exposed in succession to underpressure and to overpressure.